Carburetor for internal-combustion engines



' Feb. 19, 1924.;

c. BROWN I CARBURE'IOR FOR INTER AL COMBUSTION ENGINES FiledAug. 29.1916 v 4 Shets-Sheet 1 MENTOQ Feb 19, 1924; iAMfiS? c. BROWN CARBURETORFOR INTERNAL COMBUSTION ENGINES Fi led Aug. 29, 191s- 4 Sheets-Sheet 2 yY wvENwQ,

- 1,484,057 c. BROWN 7 4 Sheets-Sheet 5 I 6 W W 5, M w r 0 O 40 0 W .65% 4 1 v 4 mg a 1. t h v k 0 1 5 Feb. 19, 1924;

CARBORETOR FOR INTERNAL COMBUSTION ENGINES Filed Aug. 29, 1916 Feb. 19,1924; 1,484,057 0. BROWN CARBURETOR FOR INTERNAL COMBUSTION ENGINES Filed Aug. 29, 1916 4 Sheets-Sheet 4 ZMW v Patented Feb. 1 9, 1924.

" 1.484. 1 mam omen;

' CLEMENT BROWN, OF BIRMINGHAM, ZEENGLANIlZl.

GARIBURETOR FOR INTERNAL-COMBUSTION ENGINES.

Application filed August 29, 1916. Serial 110,117,506.

ply or float chamber.

' Carburetors with submerged jets are.

known in which the jets are in communication with the supply or floatchamber and wholly subject to the influence of the suction created bythe engine piston. The jet having an orifice of sufficient size to givethe correct amount of fuel at low engine speeds feeds too much fuel athigh engine speeds. To remedy this defect a second jet is pro videdwhich acts in supplementarycapacity to the first jet, equipped with asmall orifice to limit the amount of fuel fed and having and air tubeopening into the communication with the supply, whereby thejet is madeindependent of the suction created by the engine and permits fuel toflow slowly under gravity.

' It is therefore an object of the invention to provide a carburetor inwhich a single jet as is arranged, feeding into the main air passage ofthe carburetor and adapted to admit a variable quantity of fuel inaccordance with the operating conditions of the engine.

' It is a further object of the invention to provide .with a jet with anatmospheric vent in the form of a conduit communicating, at the lowerend, with a space above the jet and at the upper end with theatmosphere, the opening leading to the atmosphere being suitablyrestricted. Upon starting the suction set up by the engine will extractat v first the accumulated liquid fuel above the jet and afterwardscontinues to extractthe liquid fuel, but now from the jet which is 0then submerged. At this time the full suction effect does not act on thejet, but only a part thereof, as the air inlet of the jet; partlyneutralizes the suction effect of the engine.

It is a further object of the invention to provide a pilot jet with anair inlet having a restricted opening so as to partly neutralize thesuction effect of the engine and there: by admit variable fuelquantities. To'the accomplishment of these and re.- lated ends, thepreferred embodiments of the invention comprise the meansdescribed inthe following specification, particularly pointed out in the claimsforming a part thereof and illustrated in the accompanying' drawingswhich disclose, however, but several of the embodiments which arepredicated on the principle of the invention.

In said drawings:

' Fig. 1 is a sectlonal plan view of one form of carburetor constructedin accordance with the invention; I

' Fig. 1 is a diagrammatic view to illustrate the action of the improvedcarburetor;

Fig. 2 is a rear sectional elevation of the carburetor shown in Fig. 1,the section being taken on the line 1-2 of Fig. 1;

Figs. 3, 4, and 5 show partial sections, similar to Fig. 2 of modifiedforms of the invention. a

Fig. 3 is a diagrammatic View based on the parts shown in Fig. 3;

Fig. 4 is a diagrammatic view based on the parts shown in Fig. 4;

Fig. 5 is a diagrammatieview based on the parts shown in Fig. -5, and

' Fig. 6 showscertain details referred to in connection with Fig. 5.

Referring to the drawings, and particularly to Figs. 1, 2 and 1, theimproved carburetor has a straight air passage a and a main fuel inlet 6which opens into the air passage 03 at the throat of the Venturi tube 0,11. At a suitable distance from the inlet b a throttle member 6 isarrangedand adapted to close or substantially close the main airpassage. The carburetor is equipped with a pilot jet f communicatingwith the passage a at a point in the vicinity of the throttle c so thatwhen the latter is nearly closed an excessive draft is created in thevicinity of the vpilot jet. A main jet 9 is disposed below the normallevel of liquid fuel in the float chamber h, (as indicated in 'theseveral 'figures bydash and dotted lines) constituting a so-calledsubiqmerged jet, and communicating with the liquid fuel level in thefloat chamber h, and the lower extremity of said air conduit is incommunication with the space above the main jet 9 (Fig. 2).

A conduit 7' opens into the space above the main jet 9 and leads to aspace below a pilot jet is arranged in the pilot fuel conduit Z, whichleads to the pilot jet 7. The space above the pilot jet is has anatmospheric vent by a conduit m which, at the upper end, is suitablyrestricted by a nipple similar to the kind shown at the top of conduit2' in Fig. 4, and which, at the lower end, terminates in the space abovethe pilot jet is and below the normal liquid level. The'capacity of theinlet of the air conduit m may be suitably adjusted by means ofinterchangeable nipples, such as shown at the top of the conduit 2' inFig. 4. The arrangement of the parts is such that when the engine isstationary, fuel will stand above the main jet 9 and in the air conduit2', in the conduit j, in the space above the pilot jet is and in the airconduit m the level being indicated by dash and dotted lines in Fig. 2.

The diagrammatic view shown inFig. 1 discloses in a simplified mannerthe arrangement and communication of the several jets and conduits andalso discloses the level of a fuel.

which respectively communicate with the spaces above the main jet 9 andabove the pilot jet 70. Upon starting of the engine, at first, theliquid fuel accumulated above the jets will be extracted, causing thelatter to rush into the main air passage of the carburetor.

However, as soon as the fuel above the jets is withdrawn in thecontinued operation of the engine, further fuel is extracted from thejets but at a more moderate rate by reason of the presence of the airinlets z' and m, which communicate with the jets and'partly neutralizethe suction efiect exercised by the engine.

When the throttle e is in nearly closed position there is greatersuction in the main 421.11 passage a at the region of f than at theregion of b, so that all the fuel passes through f. When, however, thethrottle is fully open the liquid fuel is taken entirely from t e mainjet 6 and no fuel passes through f as the suction is now greater at 6than at f. The arrangement is such that so long as the negative pressurein the vicinity of the main fuel inlet 5 is suiiicient to extract liquidfrom the main jet, the pilot jet automatically remains out of action,but as soon as the throttle is so far closed that the suction in thevicinity of the main jet is insufficient to extract fuel therefrom, thefuel is taken entirely from the pilot jet.

In the modified embodiment of the present invention, as shown in Fig. 3and diagrammatically indicated in Fig. 3, the parts a, o, b correspondto the parts 9, 2' and b of the first described modification with theexception that the conduit 1' is missing. The jet n which isadvantageously used as a main jet is located in relation to the nozzle 6and this jet has an air inlet 0 and is advantageously of the submergedtype, as indicated in Fig. 3. The air inlet 0 is, at the upperextremity, equipped with a nipple 5 so as to restrict the inlet opening.A second conduit 10 independent of the first system then extends fromthe source of supply to a jet g, which communicates with an open topwell i. From this open top well a" a conduit 11 extends to a jet k, wich communicates with an air inlet chamber m, constructedsimilar to theair inlet 0. A conduit Z leads from the space above the jet is to themain air passage of the carburetor, where fuel is fed through theorifice f.

From the foregoing it is obvious that two means of feeding fuel areprovided independently from one another; one comprising the parts a, 0,b and directly communicating with the supply, and the other embracingthe elements g, k, m, Z and f and also connected to the supply. Byvirtue of the fact that the open top well '5' has not a restricted inletopening, the jet 9 feeds fuel independent of the suction existing in themain air passage and cannot deliver more than a constant uantity of fuelat unit time determinedby t e size of orifice of jet g. But beyond thisjet the air inlet m with the constricted inlet opening is provided andas a result of the presence of this air inlet m the orifice 7 does not.necessarily take all of the fuel admitbedto the valve 6 as the suctionis partly neutralized by the restricted opening in the inlet m. Undercertain conditions it may take all of this fuel, but under otherconditions it takes a less quantity. The delivery system f is thus anozzle which is variable per unit time, but which has a predeterminedmaximum delivery for it cannot take more than will flow from the jet 7-per unit time. When it has taken less than will flow per unit of time itmay take a quantity which Varies per unit of time to any extent rangingbetween zero and the maximum defined for a gravity delivery at 9. Duringthe period in which 7 is taking the available fuel, the flow at 9 wouldbe constant per unit of time. But so long as the delivery at f is lessthan a maximum of which the nozzle 9 is capable, then neither thedelivery at f or at g is constant per unit time because the excessdelivery at 9 over that delivered at f accumulates in the unrestrictedair inlet 11' and until it arrives therein to a level corresponding tothat of the liquid in the supply. Having arrived at thls level if thedelivery from 7 still continues to be less than that of which g isengine, but the suction efi'ect is moderated before it is accessible tothe second jet. As-

' is it has, after issuing from the jet 9, to

series.

by the partial atmospheric vent provided for by the air inlet conduit 0.

In a further modified embodiment of the invention, as shown in Fig. 4and diagrammatically indicated in Fig. 4, the main and pilot jets areentirely in series. Between the first jet g and the second jet krovision is made whereby a certain hea of liquid has to accumulate abovethe first jet shown, a nipple p is interposed so that before the fuel isavailable for the pilot jet rise to ahead corresponding with the top ofthe nipple p. This head reduces the gravity flow from the float chamberunder the head occurring in the float chamber. By interchanging thenipple p with one having a lower or higher top the rate of gravity flowfrom the jet g per unit time may be modi fied as requiredin connectionwith the pilot jet without affecting the delivery from the et 9 for themain nozzle 1). The jet 9' communicates with the space below'the nipplep and the nipple is disposed with its axis arranged vertically, wherebythe liquid fuel rises in the nipple and flows by gravity from the'topthereof into a chamber which is in communication with the port j of theseries passage communicating with the second of the jets which are inseries. The first jet 9' of the series is utilized as a main jet, forwhich purpose it isplaced to feed to the fuel delivery orifice b and isprovided with a conduit having a restricted air inlet 7?. The conduitcommunicates with the chamber above the interchangeable nipple p and isin communication with the main jet through the conduit in the nipple,the chamber below, the nipple and a conduit j between such chamber lastmentioned and the space above the main or first jet of the The second orpilot jet k is the same as described in connection with Figs. 1 and 2. Y

The 1i uid fuel, when the throttle is open, flows thr ugh the jet andissues through the main nozzle 6 into the main air p assage of thecarburetor. When, however, the throttle-is partially closed, the fuelmust first rise until. itreaches the top edge of grammatically the;.nipple p andv may then flow through the port j to the jet In, which isin communication with a restricted air inlet; It therefore follows thatthe action of this carburetor is identical with the action of themodification described in Figs. 1, 2 and 3 ensuring thereby a variabledelivery of fuel per unit time both for the main jet and the .pilot jetby virtue of the provision of the air inlets having a restricted openingat the upper extremity.

In a still further modified embodiment of the invention, shownin Fig. 5and diaindicated in Fig. 5, a further jet 9 is arranged in the series.This jet puts a maximum limitation upon the amount of fuel delivered perunit time by the carburetor. This jet may be disposed in the means ofcommunication between the float chamber or other source of supply and aspace below the first jet 9 An air inlet 1' is provided in connectionwith theinitial jet and as the air inlet is unrestricted the initial jetis entirely relieved from the suction effort of the engine acting, asstated before, and giving a constant maximum quantity of liquid per unittime. The discharge fromthe jet 9 may be modified by employing in placeof the jets 9 other jets g or g (Fig. 6) of differing heights on thesame principle as described in connection with nipple p in themodification shown in Fig. 4. The engine may use the full capacity ofthe jet Q, or'any less amount, in which case fuel accumulates in the airinlet '1' appertaining to the initial jet and or with t e choke, or infact with any part' of the carburetor other than the initial jet toenable the carburetor to give more than the redetermined amount of fuelas defined by t e size of the initial jet.

The above mentioned firstjet g is of such size or capacity as to givethe desired amount of fuel under the influence of the suction efi'ort ofthe engine and the liquid fuel for supplying the pilot jet is will thenissue by gravity from said first jet. If the bore of the first jetshould be such that more or less fuel issues than is required for thepilot jet, this may be corrected without altering'the capacity of thefirst jetby altering the head under which the fuel flows from the firstjet. This may be obtained by The pilot v 19,. the first jet 9, g, or 9determines the .70, is in use, so-that, as described in connection withthe initial jet in Figs. 5 and 5,

maximum amount of fuel which is supplied to the pilot jetv k or k. Thenozzle 6 or b is thus adapted to function as an air conduit when thepilot jets in or is are in use. It

' is therefore unnecessary to unduly restrict the pilot jet when thelatter is level with or;v

above the level of the liquid fuel in the float chamber and a suitablespace 70 is provided below the latter in which liquid fuel mayaccumulate to be used in starting. The pilot jet may be fed through aconduit 10 extending nearly to the bottom of this space, so that thecontained fuel may be readily extracted.

While the drawings disclose preferred embodiments of the invention, I donot wish to be limited to the exact constructional features as shown butwant to include all modifications constituting departures within thescope of theinventionas defined by the appended claims.

I claim:

1. In a carburetor for an internal combustion engine, a jet disposedbelow the normal liquid level in the supply, an air inlet inthe spacebelow said second jet, a separateand independent air inlet communicatingwith the space above said second jet, and a conduit adapted to receiveair and deliver to the main air passage of the carburetor in conjunctionwith said air the whole of the fuel received by the carburetor which isnot delivered by said second jet.

2. In a carburetor, a well, means below the normal liquid level in thesupply to supply fuel tosaid well, a restricted air inlet to the spacein said well above. said fuel supply means; asecond well having arestricted air inlet at its upper portion, a conduit connecting thelower portions of said well, a nozzle leading from said conduit at apoint intermediate its ends and-arranged to discharge into thecarburetting chamber and a second conduit leading from the lower portionof the second well to the said chamber, said first named conduit beingthereby adapted to receive air and to deliver to the carburettingchamber, in conjunction with such air, all of the fuel received by thecarburetor which is not delivered by the first namedconduit through thesecond well.

In witness whereof I have hereunto set my hand.

CLEMENT BROWN.

